...yes, performance will drop when your set of active data exceeds available memory and your system needs to reference slower storage. I assume this would apply to anything.
it's obviously based on the data size itself, memory available etc etc.
Pretty clearly people ran the exact same test, fill a table with a bunch of empty/meaningless data and see where performance degrades - then write a catchy headline title/post.
In the end, it's more nuanced than that but i think the overall theme is know your tuning once you get to certain data sizes.
